Senator Jeff Flake (R-AZ) has been one of the few Republican Senators willing to at least occasionally stand up against President Trump’s worst excesses. Naturally, that makes Flake a frequent target of Trump’s bully pulpit.

Trump’s latest attack on Senator Flake came in the form of a fact-free tweet — does Trump ever send any other kind? — that falsely claims that Martha McSally, the winner of yesterday’s Arizona Republican primary for the Senate seat that Flake is retiring from, rejected an endorsement from Flake.

Martha McSally, running in the Arizona Primary for U.S. Senate, was endorsed by rejected Senator Jeff Flake….and turned it down – a first! Now Martha, a great U.S. Military fighter jet pilot and highly respected member of Congress, WINS BIG. Congratulations, and on to November!

Senator Flake wasted no time in responding to the president’s vindictive lies. He tweeted the truth, that he hadn’t made an endorsement of any candidate in the race to replace him, adding a reminder sure to tweak Trump: that the last endorsement he made was of Democratic Senator Doug Jones in his winning race against the candidate Trump endorsed in the Alabama race, the Republican candidate and accused pedophile Roy Moore. For good measure he attached a copy of a campaign contribution check he wrote to Jones’ campaign coffers.

While Flake didn’t formally endorse McSally, he did tell reporters that he hoped she would win, reasoning that she had a better chance of keeping the Arizona Senate seat in Republican hands, given that one of her rivals in the primary was Joe Arpaio, the convicted felon whom Trump pardoned earlier this year.

Hopefully, Flake was wrong in his assessment of McSally’s chances of winning the Senate seat in the general election. With Republican governor Doug Ducey about to appoint someone to serve the remainder of the late John McCain’s term, the only real chance that Democrats have of picking up a seat in the state is if Kyrsten Sinema, the candidate who won the Democratic primary yesterday, can beat McSally in November.